Hi Alan, yes that's correct that the .3dm, .iges, .stp, and .sat formats are a more accurate way to transfer your objects to other programs, these formats contain the CAD solid/surface data. Things like a sphere surface will come over as another exact sphere surface in the receiving application rather than being approximated by a lot of little facet pieces like the polygon formats.

However, the amount of accuracy loss when converting to a mesh can often be pretty minimal so it's not necessarily a dire problem if you have to transfer data otherwise.

But yes if your CAM program that you're using for toolpath generation can accept one of those CAD files formats (3DM, IGES, STEP, or SAT formats), one of those formats (probably trying 3DM first if available then maybe STEP next) would be how you'd want to do the transfer.

Some CAM programs do only accept mesh data, and if that's the case then you would generally use STL format for transferring. That will involve a conversion of the model into a faceted representation with it being made up of a lot of little flat triangles instead of spline surfaces.

The top group, being the native NURBS, will contain the exact mathematical representation of the model data.. Your CAM package will process a toolpath from that data (Essentially dicing it up) per it's particular settings and CAM tolerances etc...

The bottom group will be your model "Diced up on export", into all "straight facets/edges" etc.... Your CAM package will have to read that, and also try to apply it's tolerances etc, to the already diced up model...

It will be preferred for you to have the NURBS data in the CAM package.